The energy density of laser light differentially modulates the skin morphological reorganization in a murine model of healing by secondary intention

Abstract

This study investigates the influence of gallium-arsenide (GaAs) laser photobiostimulation applied with different energy densities on skin wound healing by secondary intention in rats. Three circular wounds, 10 mm in diameter, were made on the dorsolateral region of 21 Wistar rats weighting 282.12 ± 36.08 g. The animals were equally randomized into three groups: Group SAL, saline solution 0.9%; Group L3, laser GaAs 3 J/cm(2); Group L30, laser GaAs 30 J/cm(2). Analyses of cells, blood vessels, collagen and elastic fibres, glycosaminoglycans and wound contraction were performed on the scar tissue from different wounds every 7 days for 21 days. On day 7, 14 and 21, L3 and L30 showed higher collagen and glycosaminoglycan levels compared to SAL (P < 0.05). At day 21, elastic fibres were predominant in L3 and L30 compared to SAL (P < 0.05). Type-III collagen fibres were predominant at day 7 in both groups. There was gradual reduction in these fibres and accumulation of type-I collagen over time, especially in L3 and L30 compared with SAL. Elevated density of blood vessels was seen in L30 on days 7 and 14 compared to the other groups (P < 0.05). On these same days, there was higher tissue cellularity in L3 compared with SAL (P < 0.05). The progression of wound closure during all time points investigated was higher in the L30 group (P < 0.05). Both energy densities investigated increased the tissue cellularity, vascular density, collagen and elastic fibres, and glycosaminoglycan synthesis, with the greater benefits for wound closure being found at the density of 30 J/cm(2).

Comparative effects of two different doses of low‐level laser therapy on wound healing third‐degree burns in rats

“…Firstly, an increase in cellular ATP production which happens due the stimulus to the electron transport chain that is inside the mitochondria is observed. Immediately afterwards, there is an increase in DNA and RNA synthesis, which then acts directly on the cell cycle regulation and favors protein synthesis, proliferation cell (Avci et al, 2013;Karu, 2010;Novaes et al, 2014;Renno et al, 2009), the angiogenesis process (Bossini et al, 2009;Colombo et al, 2013), and the action of myofibroblasts (Dantas et al, 2011;Medrado et al, 2003).…”

“…In order to obtain the aforementioned effects, the parameters employed in LLLT application should follow an adjustment that is compatible with the pathology and the depth of the tissue that received the treatment (Avci et al, 2013). However, there are discrepancies in the values that are found in literature, mainly in the protocols applied to burns (Ezzati et al, 2009;Fiorio et al, 2014;Goncalves et al, 2013;Novaes et al, 2014;Nunez et al, 2013;Renno et al, 2009). Fiorio et al (2014) assessed the effects of LLLT (660 nm) at two different fluences, 3 J/cm 2 and 4 J/ cm 2 , on third-degree burns in rats.…”

Effect of Low-Level Laser Therapy and Ultraviolet-C Irradiation on Partial-Thickness Burn Wound Healing: A Randomized Controlled Trial

“…However, Between-group differences were noteworthy, where there was a significant statistical difference post-intervention in the measured variable, WSA; where P-values were [(0.029) and (0.04), respectively]. Previous reviews have demonstrated the physiological effects of laser on wound healing through angiogenesis, proliferation of granulation tissue and diminishment in inflammatory substances [11,30]. Reviews have likewise reported the efficacy of UVC radiations on tissue healing through sterilization without biological tissue hurt, proliferation of the granulation tissues and increased circulation through angiogenesis, collateral circulation and the endothelial proliferation factors [18,26].…”

“…LLLT has evolved as a rapidly growing, noninvasive physical approach to modulate various biological processes. LLLT, for example, could cause an increase in mitochondrial respiration and ATP synthesis [8], accelerate wound healing [5,9], induce cell proliferation, promote nucleic acid production, and augment cell division [10,11,12]. In vivo studies also suggest that laser irradiation enhances collagen synthesis in the wound area resulting in increased tensile strength [13,14].…”

Effect of gallium arsenide low-level laser therapy on the inflammatory phase of skin wound healing in rats

“…The low cost of the equipment combined with promising results has generated great interest among researchers in using this technique for the modulation of tissue repair. Promising results have been observed with the use of photobiomodulation therapy (PBMT) in skin wound healing, including decreased inflammatory activity (DE ARAÚJO et al, 2007), modulation of inflammatory mediators (FIORIO et al, 2017), neovascularization (LORETI et al, 2015;NOVAES et al, 2014) and faster tissue repair (REDDY; STEHNO-BITTEL;ENWEMEKA, 2001;NOVAES et al, 2014).…”